1. Field of the Invention
The present invention relates to a semiconductor diffraction grating device and a semiconductor laser.
2. Description of the Related Art
Patent Document 1 (U.S. Pat. No. 7,145,923) describes a tuneable laser. The tuneable laser includes a reflecting section including a distributed Bragg reflector, a chirped grating section, and a gain section disposed between the reflecting section and the chirped grating section. In the chirped grating section, a chirped grating is formed such that the grating pitch monotonically increases along the length. Furthermore, the chirped grating has a sinusoidal waveform with constant amplitude.